WASHINGTON, DC (KELO) — South Dakota’s U.S. senators are citing Second Amendment rights for their opposition to a gun safety bill that passed the Senate on Tuesday. Both John Thune and Mike Rounds voted against the bi-partisan measure that includes funding for mental health and school security programs along with background checks of people under the age of 21.

Tuesday’s vote reflects a divide within the Republican party over the issue of guns and the best way to address gun violence.

The gun bill passed a procedural vote 64-34 with 14 Republicans voting in support. But South Dakota’s Mike Rounds says he wanted more time to study the bill before taking a vote.

“They only provided us with legislative text one hour before the vote was scheduled and the legislation is about 80 pages long. I’m not a real fast reader when it comes to that,” Rounds said.

Senator Thune’s office emailed KELOLAND News a statement saying “After reviewing the contents of this legislation and hearing feedback from law-abiding gun owners in our state, I do not believe this bill is something that South Dakotans support.”

Yet the senate’s top Republican, Minority Leader Mitch McConnell voted in favor of the bill.

“Someone who has never been convicted of a violent crime, or adjudicated as mentally ill, will not have their rights affected one iota,” McConnell said.

But Rounds says the bill’s closing of the so-called “boyfriend loophole” goes too far.

“If you have a young couple that would have an argument and if one of the two individuals is found guilty of a misdemeanor offense in the altercation, a misdemeanor, they lose their Second Amendment rights for a period of five years. I think that’s moving in the wrong direction for a misdemeanor violation,” Rounds said.

The Senate is expected to take a final vote later in the week before the bill moves onto the House. The bill is expected to pass the Senate, but Rounds says he’ll likely be a no-vote, once again.

The bill, if passed, would be the most significant piece of gun reform legislation in nearly 30 years. But Rounds says members of the Senate will not be allowed to include amendments to the bill, which is another reason he’s opposing it.